1. Field of the Invention
The present invention is directed to an improved process and system for the production of hydrogen-rich gas by the steam reforming of hydrocarbons. More specifically, the present invention involves a low energy process and system for the production of ammonia synthesis gas including the process steps of primary and secondary reforming for producing hydrogen-rich gas which includes the parallel primary reforming of the hydrocarbon feed, one portion of the hydrocarbon feed being heated using radiant heating and another portion being heated using indirect heat exchange with the effluent from the secondary reforming.
2. Prior Art
U.S. Pat. No. 3,094,391 discloses a steam reforming furnace having a reaction radiant-heating section and a reaction convection-heating section. A portion of the hydrocarbons is passed to tubes in the radiant-heating section of a furnace, and the balance of the hydrocarbons is passed in parallel to tubes provided in the reaction convection-heating section for steam reforming.
A conventional steam reforming furnace is disclosed in U.S. Pat. No. 3,257,172 and in a conventional process, as disclosed in U.S. Pat. No. 3,441,393, the steam reforming furnace is the sole system for carrying out the steam reforming reaction.
U.S. Pat. No. 3,549,335 discloses a reactor wherein the hydrocarbons are steam reformed in the lower portion of an inner shell having a container for secondary catalyst thereabove and a process for primary and secondary reforming in the same reactor is carried out.
U.S. Pat. No. 3,751,228 discloses an apparatus for reforming hydrocarbons under pressure comprising a heat-exchange chamber incorporating reaction tubes for effecting a process of primary reforming and a shaft chamber for effecting a process of secondary reforming located at the open ends of the reaction tubes.
U.S. Pat. No. 3,958,951 discloses a reformer furnace having a convection section, means for preventing radiant heat from the burners to the convection section, a centrally disposed effluent tube suspended from the top of the furnace, a tube sheet surrounding and suspended from the centrally disposed effluent tube and reformer tubes suspended from the tube sheet which reformer tubes are in communication with the interior of the effluent tube.
U.S. Pat. No. 3,870,476 discloses a pressure vessel for catalytic endothermic reactions in the upper portion of which is a supporting plate for a plurality of open ended shell tubes within which are reaction tubes.